Calling owners to share MPG of an FD3S so I can compare it my MR2 Turbo 380 fbhp

[Will66]

Anything with a rotary is very poor on fuel, even the supposedly fuel efficient RX8 struggles to get near 30 mpg unless you drive very slowly, RX8s hate being driven slowly.  It causes the second and third stage valves in the intake to stick and restricts performance.

[fil_auto]

That\'s FDUKin amazing Blitzen! Are you sure you didn\'t mean 22mpg??!!

TBH The best I ever got was 32mpg on mine, 60-65mph for an hour just above idle for my engine, I only had 10 quids worth of fuel as I forgot my wallet at home so I had to go slow for once, I was praying it wouldnt run out and stop.
It was leaned right out in that part of the map

[BlitzBoy]

yip 32 mpg.
You get a lot of overlap in a half bridge, hence unburnt fuel gets ingested in the next cycle at low rpm, therefore you dont need to inject as much fuel in the map, plus you are not on boost in a single turbo at those sort of rpm, reason why twins burn a bit more fuel then singles as you are on boost more at low rpms.
Running 16:1 afr in that part of the map, some engines are ok with that some not and will buck as it were.

But I drive a rotary how it should be driven, hard, who gives a feck about mpg in a sports car.

[fil_auto]

Awesome and exactly

[Sanchi]

I appreciate the comments guys, but just to remind you I\'m not worried about the MPG as much as I wanted to make a comparison that all, but thanks for the information so far its great!  

im in japan, slow easy driving 35mpg all day. driving like its stolen 10mpg.
your mr2 is nothing compared to what a rx can do.

I appreciate that, I just wanted to make a comparison. I merely mentioned it would be close to a 7 around town, I have mentioned the engine is not stock and heavily modified. I do understand they aren\'t the same so I wanted to find out the difference

I\'ve said it before and probably will do again....life is just to short to care about MPG. Rotaries are really, really shlte on fuel economy, don\'t buy one if you care about stuff like that. I get around 250 miles to a tank (about £60-£70 quid on current prices) and thats on a 400 bhp single. Haven\'t ever given enough fduks to work that out into mpg numbers!

What you will get as a massive improvement over an MR2 is handling, involvement, looks, performance, build quality and exclusivity. Not to mention an engine bay you don\'t have to be a proctologist to work in! Having owned both, I can assure you that there is just no basis for comparison between the two

Lol. I do agree on the engine part. I built my own engine from scratch fully forged, head, cams etc and it is a fun challenge working back there! The only comparison I was making is the MPG as mine is also quite heavy on the fuel as it has larger 870cc injectors, fuel rail and braided fuel lines etc so just wanted an idea as I am looking to buy an RX7 once I find a buyer. When mapping mine can make 400 bhp it just needs a 3 bar map sensor as it is quite an old school turbo I am using.

When I went to the ring in sept 10 motorway driving at 60-70 mph got me 150 miles from full to half a tank and thats the best I could do off boost. Another time I had a full tank and went from west london to folkestone to catch the ferry was running late and I got 80-90 miles to a full tank.

I do understand its all about how you drive as you can stay off boost and preserve some fuel.


I do believe that the 7 would be a good upgrade from the MR2.

[BlitzBoy]

The only comparison I was making is the MPG as mine is also quite heavy on the fuel as it has larger 870cc injectors,.

wow they are small :rollin Jokin, its only because Im running 4x1680 :Hammer

You will get used to the idea of modified rotarys and large injectors go hand in hand :3gears-lh

[Sanchi]

wow they are small :rollin Jokin, its only because Im running 4x1680 :Hammer

Fair Play, those are quite big. But its not about the size its how you use them Lol.

As you know its about what works with your application. For me thats double the original size! Lol.

Also one other thing, how is the engine in this type of cold weather, I\'ve heard some stories of the engine having a problem at cod start up in the cold? Can you clarify anything to do with this. i.e mixtures of AFR or something with a lean mixture? Thanks.

[Sanchi]

In all seriousness, the words RX7 and fuel efficiency / MPG do not go together! They are simply not fuel efficient and need to be driven and driven hard.... ( most of the time)

ATB Phil

Anything with a rotary is very poor on fuel, even the supposedly fuel efficient RX8 struggles to get near 30 mpg unless you drive very slowly, RX8s hate being driven slowly.  It causes the second and third stage valves in the intake to stick and restricts performance.

Hey guys thanks for the comments. I know they are not fuel efficient, my aim for this post was to get an idea of real data from actual owners rather than read a generic article, also to compare it to my MR2 Turbo which I am currently writing a for sale ad for as I am looking to upgrade to an RX7

[Jono FD3]

mine is about the 330bhp and on a run I am getting about 21-22mpg sat at about 75 (30 miles of A roads & 75mile motorway going to cardiff).... but open the taps and you can watch the needle drop! LOL

[Nik da Greek]

Also one other thing, how is the engine in this type of cold weather, I\'ve heard some stories of the engine having a problem at cod start up in the cold? Can you clarify anything to do with this. i.e mixtures of AFR or something with a lean mixture? Thanks.

Yeah, mixtures aren\'t too clever atm. When I left work last night it was -3 and the air intake temp never got higher than 8 degrees all the way home . AFRs were all over the place....not that I was likely to use much boost, it was slippery as fduk and more than a bit lively on all the ice without boosting up :Hammer

I\'ve only got 2x850 and 2x1680 injectors but then mine is a hell of a bit slower than Blitzens lol, means I can get away with a nice economical setup :rollin

[hairyhoover]

its all about how you map it lads.

driving to work and back i get 20mpg, on the motorway i get 27-28mpg, last time i did a drive down to wales i averaged 27.7mpg, done 28.2mph before going down to surrey.

if your cruising down the motorway at 70mph pulling 15in of vac do you really need to be sticking loads of fuel in? i run around 15.5-16afr in those load points to give me good economy

What plugs are you running? Do you worry and them getting to hot after a while with these arf,s. It become a problem when you put heavy boost on when they really hot.

[turbotoaster]

im running 9s all around.

Why should i worry about running hot, its deep into vaccum so under no load, my EGTs will be a little higher than when they are getting fuel dumped over them but there is no damage.

Happily sit at 82c water temp all day crusing down the motorway like that.

When you put your foot down it doesnt go from crusing to full boost in 0.01sec so when the accelarator is pressed the fueling richens up.

For reference this is how i set my fuelling.


vac motorway cruising 15.5-16afr(try to aim for 16 as much as possible)
vac crusing at low speed 14.2-14.8 afr
0 boost(ie tip in from vac to boost) 13.2afr
5psi of boost 12.3afr
10psi of boost 11.7afr
17psi of boost 11.0afr
20psi of boost 10.8afr

dont have water injection yet so run a little richer past 17psi for safety.

[Sanchi]

Great information guys. Thanks.

Just out of interest in the MR2 community I know who i used for mapping. In the RX7 community who is renowned for their mapping and who is used with high recommendations?

[goldk28611]

Great information guys. Thanks.

Just out of interest in the MR2 community I know who i used for mapping. In the RX7 community who is renowned for their mapping and who is used with high recommendations?

Jason at Super7 gets my vote... do a search on here and other forums - never a bad word said about the bloke or his work... (he sorted millions of problems with mine and now is a reliable daily) good prices too!

[Nik da Greek]

+1 for Super7 (perhaps predictably lol). Jason\'s sorted out more problems with mine over the years than I can actually remember, always with a cup of tea and good natured-humour involved haha. He now does his own mapping too in association with Matt at AFR Tuning, and they\'ve managed to get me a reliable 400 hp daily out of a little old-skool tub like a T04S